Add File types to the Microsoft Outlook Attachment Manager

Microsoft Outlook categorizes mail attachments into three risk types which are high, medium and low. Outlook uses the default Microsoft configuration to determine if a file poses a high, medium or low risk when the user tries to open the attachment. The file extension .exe for instance poses a high risk while .txt does not and is seen as a low risk file extension. If a file type has not been specified by Microsoft it is seen as a medium risk. Microsoft Outlook can block or display warning messages whenever the user tries to open a file type that is seen as a high or medium risk.

This is probably not a problem for most users but if you do get lots of files of a certain type - at work for instance - then you might want to change the default configuration and lower the risk setting of that specific file type. The following tip is also explaining how users can add new file types to the attachment manager and assign a risk level to them.

We need to open the Windows Registry because the custom settings have to be added to the Registry. Press Windows R, type regedit and hit enter. Now navigate to the Registry key HKEY_CURRENT_USER \Software \Microsoft \Windows \CurrentVersion \Policies. Right-click the Policies key and select New -> Key and name that key Associations.

Three DWORD values define additions to the risk settings of the Outlook Attachment Manager. They are:

HighRiskFileTypes
ModRiskFileTypes
LowRiskFileTypes

If you wanted to add some file types as low risks you would create a new DWORD and name it LowRiskFileTypes. The value of the key can be changed by double-clicking it. Now add file types to it and separate them with a “;”. To add .exe and .avi as a value you would add the following string in that field: “.exe;.avi”